The ASCENTS 121 support for science programme trained STEM undergraduates to provide 23 weekly one-to-one academic mentoring sessions to Year 11 science pupils with the aim of improving GCSE science attainment. Mentees were all eligible for free school meals and predicted to achieve a level 3-5 in GCSE science. Sessions were delivered outside of school hours (before or after school) in classrooms or laboratories under the supervision of a teacher. The topic of each session was chosen by pupils. The University of Lincoln led the programme, supported by the University of Leeds, the University of Liverpool, UCL’s Institute of Education and the University of York.